排序方式: 共有52条查询结果,搜索用时 15 毫秒
1.
2.
Tatjana Krama Arnis Bērzi?? Seppo Rytk?nen Markus J. Rantala David Wheatcroft Indrikis Krams 《Acta ethologica》2012,15(1):127-134
In habitats where the density of breeding individuals is higher, breeding success has been shown to increase with the number
of close conspecific and heterospecific neighbours. However, the mechanisms linking habitat quality, group size of prey individuals
and offspring defence are poorly known. In this field study, we examined the relationships between habitat quality and parental
nest defence behaviour in the pied flycatcher (Ficedula hypoleuca). We found that mobbing is more intense in unmanaged forests where birds breed in more dense and diverse communities than
in heavily managed young forests where heterospecific densities are lower. We also found that the mobbing activities of pied
flycatchers breeding in unmanaged mature boreal forests attracted more neighbouring prey individuals than in nearby managed
forests. This study shows that habitat quality-mediated effects might be responsible for the decreased group size of mobbing
birds in managed forests, which may lead to less effective communal defence. 相似文献
3.
4.
The simultaneous action of shear deformation and high pressure (SDHP) creates changes in the structure of wood and its main
components (cellulose, hemicelluloses, lignin). The formation of water and alkali soluble polysaccharides under SDHP action,
proceeds in seconds in the solid state, without the use of any reagents and solvents. Therefore, SDHP seems to be a technologically
safe method and friendly to the environment. The amorphization of cellulose crystallites and depolymerization of cellulose
chains were observed under a wide range of pressures (1–6 GPa), both for cellulose samples and the cellulose part of wood.
Similar depolymerization occurs in the hemicellulose part of wood. The decomposition of polysaccharides under SDHP causes
the formation of the water soluble part, whose content increases with pressure and the applied shear deformation. A maximum
solubility of 40% and 55% was registered at 6 GPa following treatment of cellulose and birch wood samples. A higher output
in the case of wood can be explained by a specific role of lignin under SDHP, which acts as a ‘grinding stone’ during cellulose
and hemicelluloses destruction. As shown by high-performance size exclusion chromatography, the water soluble fraction obtained
from cellulose contained glucose (2.6%), cellobiose (9.6%), cellotriose (16.6%) and other higher water soluble oligomers (71%).
Almost complete dissolution (98%) of the treated cellulose sample can be achieved by extraction with 10% NaOH solution. The
SDHP treated birch wood was subjected to submerged fermentation (with Trichoderma viride), and a 13% output of proteins was
obtained. In this case, the water soluble part played the role of the so called ‘start sugars’. Abbreviations: ASF, alkali
soluble fraction; DP, degree of polymerization; EC, energy consumption; HP, high pressure; LMWS, low molecular weight sugars;
MC, moisture content; MCC, microcrystalline cellulose; SD, shear deformation, SDHP, shear deformation under high pressure;
SS, shear strength; WSF, water soluble fraction
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
5.
Song BK Hein I Druka A Waugh R Marshall D Nadarajah K Yap SJ Ratnam W 《Functional & integrative genomics》2009,9(1):97-108
Common wild rice (Oryza rufipogon) plays an important role by contributing to modern rice breeding. In this paper, we report the sequence and analysis of a
172-kb genomic DNA region of wild rice around the RM5 locus, which is associated with the yield QTL yld1.1. Comparative sequence analysis between orthologous RM5 regions from Oryza sativa ssp. japonica, O. sativa ssp. indica and O. rufipogon revealed a high level of conserved synteny in the content, homology, structure, orientation, and physical distance of all
14 predicted genes. Twelve of the putative genes were supported by matches to proteins with known function, whereas two were
predicted by homology to rice and other plant expressed sequence tags or complementary DNAs. The remarkably high level of
conservation found in coding, intronic and intergenic regions may indicate high evolutionary selection on the RM5 region.
Although our analysis has not defined which gene(s) determine the yld1.1 phenotype, allelic variation and the insertion of transposable elements, among other nucleotide changes, represent potential
variation responsible for the yield QTL. However, as suggested previously, two putative receptor-like protein kinase genes
remain the key suspects for yld1.1.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Christoph Dockter Damian Gruszka Ilka Braumann Arnis Druka Ilze Druka Jerome Franckowiak Simon P. Gough Anna Janeczko Marzena Kurowska Joakim Lundqvist Udda Lundqvist Marek Marzec Izabela Matyszczak André H. Müller Jana Oklestkova Burkhard Schulz Shakhira Zakhrabekova Mats Hansson 《Plant physiology》2014,166(4):1912-1927
Reduced plant height and culm robustness are quantitative characteristics important for assuring cereal crop yield and quality under adverse weather conditions. A very limited number of short-culm mutant alleles were introduced into commercial crop cultivars during the Green Revolution. We identified phenotypic traits, including sturdy culm, specific for deficiencies in brassinosteroid biosynthesis and signaling in semidwarf mutants of barley (Hordeum vulgare). This set of characteristic traits was explored to perform a phenotypic screen of near-isogenic short-culm mutant lines from the brachytic, breviaristatum, dense spike, erectoides, semibrachytic, semidwarf, and slender dwarf mutant groups. In silico mapping of brassinosteroid-related genes in the barley genome in combination with sequencing of barley mutant lines assigned more than 20 historic mutants to three brassinosteroid-biosynthesis genes (BRASSINOSTEROID-6-OXIDASE, CONSTITUTIVE PHOTOMORPHOGENIC DWARF, and DIMINUTO) and one brassinosteroid-signaling gene (BRASSINOSTEROID-INSENSITIVE1 [HvBRI1]). Analyses of F2 and M2 populations, allelic crosses, and modeling of nonsynonymous amino acid exchanges in protein crystal structures gave a further understanding of the control of barley plant architecture and sturdiness by brassinosteroid-related genes. Alternatives to the widely used but highly temperature-sensitive uzu1.a allele of HvBRI1 represent potential genetic building blocks for breeding strategies with sturdy and climate-tolerant barley cultivars.The introduction of dwarfing genes to increase culm sturdiness of cereal crops was crucial for the first Green Revolution (Hedden, 2003). The culms of tall cereal crops were not strong enough to support the heavy spikes of high-yielding cultivars, especially under high-nitrogen conditions. As a result, plants fell over, a process known as lodging. This caused losses in yield and grain-quality issues attributable to fungal infections, mycotoxin contamination, and preharvest germination (Rajkumara, 2008). Today, a second Green Revolution is on its way, to revolutionize the agricultural sector and to ensure food production for a growing world population. Concurrently, global climate change is expected to cause more frequent occurrences of extreme weather conditions, including thunderstorms with torrential rain and strong winds, thus promoting cereal culm breakage (Porter and Semenov, 2005; National Climate Assessment Development Advisory Committee, 2013). Accordingly, plant architectures that resist lodging remain a major crop-improvement goal and identification of genes that regulate culm length is required to enhance the genetic toolbox in order to facilitate efficient marker-assisted breeding. The mutations and the corresponding genes that enabled the Green Revolution in wheat (Triticum aestivum) and rice (Oryza sativa) have been identified (Hedden, 2003). They all relate to gibberellin metabolism and signal transduction. It is now known that other plant hormones such as brassinosteroids are also involved in the regulation of plant height. Knowledge of the molecular mechanisms underlying the effects of the two hormones on cell elongation and division has mainly come from studies in Arabidopsis (Arabidopsis thaliana; Bai et al., 2012). Mutant-based breeding strategies to fine-tune brassinosteroid metabolism and signaling pathways could improve lodging behavior in modern crops (Vriet et al., 2012) such as barley (Hordeum vulgare), which is the fourth most abundant cereal in both area and tonnage harvested (http://faostat.fao.org).A short-culm phenotype in crops is often accompanied by other phenotypic changes. Depending on the penetrance of such pleiotropic characters, but also the parental background and different scientific traditions and expertise, short-culmed barley mutants were historically divided into groups, such as brachytic (brh), breviaristatum (ari), dense spike (dsp), erectoides (ert), semibrachytic (uzu), semidwarf (sdw), or slender dwarf (sld; Franckowiak and Lundqvist, 2012). Subsequent mutant characterization was limited to intragroup screens and very few allelism tests between mutants from different groups have been reported (Franckowiak and Lundqvist, 2012). Although the total number of short-culm barley mutants exceeds 500 (Franckowiak and Lundqvist, 2012), very few have been characterized at the DNA level (Helliwell et al., 2001; Jia et al., 2009; Chandler and Harding, 2013; Houston et al., 2013). One of the first identified haplotypes was uzu barley (Chono et al., 2003). The Uzu1 gene encodes the brassinosteroid hormone receptor and is orthologous to the BRASSINOSTEROID-INSENSITIVE1 (BRI1) gene of Arabidopsis, a crucial promoter of plant growth (Li and Chory, 1997). The uzu1.a allele has been used in East Asia for over a century and is presently distributed in winter barley cultivars in Japan, the Korean peninsula, and China (Saisho et al., 2004). Its agronomic importance comes from the short and sturdy culm that provides lodging resistance, and an upright plant architecture that tolerates dense planting.Today, more than 50 different brassinosteroids have been identified in plants (Bajguz and Tretyn, 2003). Most are intermediates of the complex biosynthetic pathway (Shimada et al., 2001). Approximately nine genes code for the enzymes that participate in the biosynthetic pathway from episterol to brassinolide (Supplemental Fig. S1). Brassinosteroid deficiency is caused by down-regulation of these genes, but it can also be associated with brassinosteroid signaling. The first protein in the signaling network is the brassinosteroid receptor encoded by BRI1 (Li and Chory, 1997; Kim and Wang, 2010). In this work, we show how to visually identify brassinosteroid-mutant barley plants and we describe more than 20 relevant mutations in four genes of the brassinosteroid biosynthesis and signaling pathways that can be used in marker-assisted breeding strategies. 相似文献
7.
Staniszewska M Słuczanowska-Głąbowska S Drukała J 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2011,49(3):375-380
Stem cells represent a great hope for regenerative medicine. In adult life, stem cell deposits are kept in organ niches; the need for tissue or organ regeneration mobilizes stem cells via the SDF-1-CXCR4 regulation axis. Constant regeneration of the skin is achieved due to stem cell differentiation within the epidermis and the hair follicle; thus, skin may serve as an excellent source of stem cells. This is of paramount importance in the treatment of chronic skin wounds and burns. 相似文献
8.
Indulis Cielens Ludmila Jackevica Arnis Strods Andris Kazaks Velta Ose Janis Bogans Paul Pumpens Regina Renhofa 《Molecular biotechnology》2014,56(5):459-469
The virus-neutralising domain III (DIII) of the West Nile virus glycoprotein E was exposed on the surface of RNA phage AP205 virus-like particles (VLPs) in mosaic form. For this purpose, a 111 amino acid sequence of DIII was added via amber or opal termination codons to the C-terminus of the AP205 coat protein, and mosaic AP205-DIII VLPs were generated by cultivation in amber- or opal-suppressing Escherichia coli strains. After extensive purification to 95 % homogeneity, mosaic AP205-DIII VLPs retained up to 11–16 % monomers carrying DIII domains. The DIII domains appeared on the VLP surface because they were fully accessible to anti-DIII antibodies. Immunisation of BALB/c mice with AP205-DIII VLPs resulted in the induction of specific anti-DIII antibodies, of which the level was comparable to that of the anti-AP205 antibodies generated against the VLP carrier. The AP205-DIII-induced anti-DIII response was represented by a significant fraction of IgG2 isotype antibodies, in contrast to parallel immunisation with the DIII oligopeptide, which failed to induce IgG2 isotype antibodies. Formulation of AP-205-DIII VLPs in alum adjuvant stimulated the level of the anti-DIII response, but did not alter the fraction of IgG2 isotype antibodies. Mosaic AP205-DIII VLPs could be regarded as a promising prototype of a putative West Nile vaccine. 相似文献
9.
A new juno iris for the Flora of Afghanistan, Iris furseorum T. Hall & Seisums, is described and illustrated. It was collected in N.E. Afghanistan by Paul and Polly Furse in 1966 and has been maintained in cultivation. 相似文献
10.